The present invention relates to an image data communication system, and more particularly to an image data communication system and a method thereof for displaying on an image display apparatus an image signal which is generated by imaging a subject. The present invention also relates to an image pickup apparatus and an image data processing method used for the image data communication system.
A portable information device, especially a portable telephone, has a limited image data processing capability and often places limitations on the amount of data and the number of colors as regards available digital images. Accordingly, displaying an image on the portable information device requires advanced knowledge about digital images, such as an image retouching program, for example.
To solve this problem, there are provided cameras dedicated to a portable device for displaying images and a special conversion program for a personal computer. An image is created by using these hardware and software products and is input to the portable device according to a special communication protocol.
According to an available service, an image processing server is provided on the network. An image is once uploaded to the image processing server. The uploaded image is automatically converted according to the amount of data and the number of colors which can be processed on the portable information device. The converted image is then downloaded to the portable information device.
When a dedicated communication protocol is used for entering the created image to the portable device as mentioned above, special-purpose devices or programs are needed, increasing costs and causing a compatibility problem.
According to the above-mentioned method, an image processing server is provided on the network and the created image is uploaded for converting the data amount and the number of colors. This method solves the compatibility problem but necessitates additional communication costs. Currently, a mainstream digital still camera is capable of digital images of more than a million pixels, whereas a portable information device supports images of just several tens of thousands of pixels at the most. This results in uploading data several tens of times larger than the number of pixels finally needed, causing unnecessary communication costs. Since the amount of data is compressed considerably, there is a high possibility of degrading the quality of converted images. The conventional method allows confirmation of the image quality only after completion of all processes. There has been frequently a waste of time, communication costs, and charges for the service.